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Finding the Fourth Proportional to 38.78, 58.13 and 20.72

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Solution

The fourth proportional to 38.78, 58.13 and 20.72 is: 31.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.78 : 58.13 = 20.72 : x
  2. Step 2: Convert to fraction form
    38.78/58.13 = 20.72/x
  3. Step 3: Cross multiply
    38.78x = 58.13 × 20.72
  4. Step 4: Simplify right side
    38.78x = 1,204.57
  5. Step 5: Solve for x
    x = 1,204.57/38.78
  6. Step 6: Final answer
    x = 31.07

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.